Adhesion of nanoparticles to surfaces has been accomplished via a number of mechanisms, such as chemical modification of the surface or nanoparticles (as in the case of gold particles adhered via thiols) or surface modification (increased surface roughness generally leading to greater contact and adhesion). However, many of these methods suffer from continued issues of adhesion strength along with associated problems of surface irreproducibility and surfaces that are easily damaged, resulting in a lack of commercially viable products.
In the case of glass surfaces, it has been shown that it is possible to adhere nanoparticles to the glass via a thermal sintering step. In the sintering process, the glass structure was heat treated, for example at a temperature near the softening point, enabling the adhesion of nanoparticles to the surface. Typically, the nanoparticles chosen had higher Tm or Tsoft than the structure glass, allowing for very good control over the amount of sintering of the nanoparticle to the structure and allowing the nanoparticles to be embedded into the glass structure up to one-half of the particle diameter or more. However, in some embodiments, the sintering temperature varied significantly as a function of the particle diameter, with larger diameter particles requiring higher temperatures. For example, a monolayer of silica 100-120 nm nanoparticles on Corning glass code 2318 required a temperature of 725-750° C. to sinter the nanoparticles to one-half the diameter into the glass surface, whereas a monolayer of 250 nm nanoparticles required a temperature of 750-770° C. Further, since the adhesion happens at a temperature higher than the anneal temperature of the glass, this results in softening of the glass which may enable deformation and warping. Therefore, there is a continued need to find new methods of adhering particles to surfaces that provides a tough surface that retains the desired chemical and physical attributes of the nanoparticle-modified surface.